Version 17 (modified by bernardt, 8 years ago) (diff)


| dCache Hands-on Taipei |


We would like to ask every participant to bring a notebook that has some kind of ssh client installed. Please check on your machine.

You need to login to your virtual machines (VMs). You have two VMs, one server and one client:

  • <user number>
  • <user number>

You will have to use two consoles, one for the server and one for the client. Use your ssh-client to connect to the machines using the following commands.


ssh dcache-user@<user number> -A -X


ssh root@<user number> -A -X

After this step you should have to consoles with ssh connections to server and client. Make sure you know which console is the client, which is the server.

Content of the hands-on

In this hands-on we will cover the following topics

  • Installation of dCache server
  • Interaction with dCache
  • Certificates and dCache
  • Hardware Lifecycle (adding storage, migrating)
  • Interfacing with Tertiary Storage

Installation of dCache server


I this part we install dCache and at the end have a running dCache that can be mounted locally as well as on your client.

  1. Find the dcache server rpm on your server in /root/: dcache-2.5.0-1.noarch.rpm
  2. Install the rpm on your server machine:
    rpm -ivh dcache-2.5.0-1.noarch.rpm

dCache server has two dependencies: java-1.7.0-openjdk, postgresql-server (version >8.4). You will find that openjdk and postgresql-server are already installed on your machine and postgresql setup was done for you already.

rpm -qa |grep -E "postgresql-server|java-1.7.0-openjdk"

For more information on this please see dCache Book - Prerequisites. There are also several trivial steps that you have to do to setup postgresql, but they are not part of this tutorial and can be found in dCache Book - Readying the PostgreSQL server for the use with dCache

There are several configuration files that can be used to configure dCache:

  • General Configuration: /etc/dcache/dcache.conf
  • Layout Configuration: /etc/dcache/layouts/head.conf
  • Security Configuration: /etc/dcache/gplazma.conf

Details on what configuration can done in dCache can be found in these files: /usr/share/dcache/defaults/*.properties. The properties described in these files should not directly be altered in the files, but should rather be taken to /etc/dcache/dcache.defaults or to the layout file in /etc/dcache/layouts/ and modified there.

We would like to have our own layout file that we just use for this hands-on, therefor we create it from a template:

cp /etc/dcache/layouts/single.conf /etc/dcache/layouts/taipei.conf

We need to add this to /etc/dcache/dcache.conf


Then we need to tell dCache that it should use this layout file, which we do by editing the /etc/dcache/dcache.conf file:

vi /etc/dcache/layouts/taipei.conf

These lines need to be added at the end of the file:


Before we can start dCache we have to empty /etc/dcache/gplazma.conf as there is no security configured in a blank dCache:

echo "" > /etc/dcache/gplazma.conf

Now start dCache by:

dcache start

Check if dCache has started up correctly by first entering:

dcache status

Then also check the log files:

tail -F /var/log/dcache/*

First Contact

Now that we have a running dCache that does nothing we would like to make a first contact. This will be achieved by mounting dCache locally via NFSv41. First edit the /etc/dcache/dcache.conf so it looks like this

dCache needs something that holds that actual data, the pools. So we first create a pool that is stored on a certain path, set its maximum size.

dcache pool create --size=419430400 /pools/nfsPool nfsPool poolDomain

After we created the pool we need to start the domain it was created in:

dcache start poolDomain

This now enables us to actually store files in dCache, but how? ... via a mounted NFSv41.

nfs.domain = taipei

Now we need to create a directory in dCache:

chimera-cli mkdir /data

Then we restart dCache:

dcache restart

After this we can mount dCache locally by doing the following:

mkdir -p /nfs/4
mount -o intr,minorversion=1 localhost:/data /nfs/4

Now we have to give the directory the right permissions:

chown -R dcache:dcache /nfs/3/ 

Interaction with dCache

In this section we will look at the different ways of interacting with dCache to make use of its functionality.

Certificates and dCache

This part will have a look at the security mechanisms that are used within the Grid.

Hardware Lifecycle (adding storage, migrating)

Here you will see how to maintain a dCache that is in production. This part will include adding storage and migrating data.

Interfacing with Tertiary Storage

Finally we will look at how dCache can be used to access archive media (tape archives)